1. Field of the Invention
The present invention relates to a magnetic sensor.
2. Related Background Art
As magnetic sensors used in thin-film magnetic recording and reproducing heads and the like, magnetoresistive (MR) devices utilizing giant magnetoresistive effect (GMR), tunnel magnetoresistive effect (TMR), and the like have conventionally been known.
In general, a GMR device has a multilayer structure in which a free magnetization layer, a nonmagnetic conductive layer, a fixed magnetization layer, and an upper electrode are sequentially formed on a lower electrode. A typical TMR device has a multilayer structure in which a free magnetization layer, a nonmagnetic insulating barrier layer, a fixed magnetization layer, and an upper electrode are sequentially formed on a lower electrode. Such a magnetoresistive device in which a free magnetization layer and a fixed magnetization layer are laminated in a vertical direction will hereinafter be referred to as vertical spin-valve device. For measuring a magnetic field from a minute area, it has been desired for the vertical spin-valve device to lower the height in the laminating direction.
On the other hand, a spin accumulation (SA) magnetic sensor in which a free magnetization layer and a fixed magnetization layer are formed on the same horizontal surface (nonmagnetic conductive layer for accumulating spins) has been known (see, for example, Japanese Patent Application Laid-Open No. 2007-299467 and Japanese Patent Publication No. 4029772), which will hereinafter be referred to as lateral spin-valve device.